In view of the unique composition of hair fibers and the various changes in styles and fashion, the waving of hair has long been of particular interest. In order to best understand the various methods in which hair fibers can be styled or waved, it is important to remember that normal hair has three major bonds that hold the configuration of the hair and are responsible for the strength of the hair. These three bonds are salt linkages, hydrogen bonds, and disulfide bonds.
As is well known, hair is a protein produced from units known as "amino acids". A high proportion of these are diamino and dicarboxylic "amino acids", and thus the hair fiber is amphoteric in character. Since the number of free acid and basic groups are approximately equal, the hair's mechanical properties, such as its strength, is at its maximum at neutrality (pH 7). For example, the fiber becomes easier to stretch as the pH increases or decreases from pH 7. The cohesion of hair is also demonstrated by the minimum swelling in water at neutrality.
Because they are so numerous, the hydrogen bonds, involving the amino hydrogen and carbonyl oxygen of the amide linkages, are most important. Water, particularly in the monomolecular state, as occurs with moisture in the air (humidity), can weaken these bonds, by becoming a part of a hydrogen bonding structure. However, some of these hydrogen bonds are protected by hydrophobic bonds and will remain even when the hair is wet with water. More powerful hydrogen bond breakers, like high concentration of lithium bromide and urea are required for complete breakage of all hydrogen bonds.
As long as the hair fiber is dry, the strength of the hair fiber is not reduced. For example, a straight hair, wet with water and held by mechanical force in a curly configuration while drying will remain in a curly shape due to the formed hydrogen bonds and salt linkages, and it will not return to its straight shape so long as it remains dry. However, unless mechanically restrained, upon being wet with water, the hair will lose its curly configuration and become straight.
Furthermore, when hair is set by the use of water alone, the hair will gradually lose its curly shape through the absorption of atmospheric moisture and the resulting rearrangement of the hydrogen bonds. This is due to the fact that in water, the dominant bond is disulfide bond, while in the dry state, the dominant bonds are the salt linkages and the hydrogen bonds.
In regard to the disulfide bonds, hair is composed of a unique protein material called "keratin", which is distinguished by the fact that it contains a very significant amount of an amino acid (cystine) which contains the element sulfur in addition to the elements nitrogen, oxygen, carbon and hydrogen. In the natural synthesis of hair, the element sulfur covalently links adjacent polypeptide chains (K) through two sulfur atoms (S-S) to give keratin protein (K-S-S-K). Only by chemical action can this covalent linkage be broken.
Similarly, it is well established that in order to permanently wave hair, this disulfide linkage must be broken. In this regard, many prior art compositions have been developed for the "cold permanent waving" of hair. Typically, these prior art systems treat the hair with a reducing agent which breaks the disulfide (cystine) linkage in the hair while the hair is wound around a curling rod. These prior art systems are typified by the disclosures in U.S. Pat. Nos. 2,479,382, 2,577,710, 2,577,711, 2,688,972, and 2,708,940.
It is believed that certain hydrogen bonds are protected by the cystine bond and are only broken by water when the cystine bond is split into two cysteine moieties. By the same rationale, these hydrogen bonds are re-formed in the new configuration and protected by the newly formed cystine bonds created in the neutralization step of permanent waving. In effect, these protected hydrogen bonds supplement the disulfide bonds in creating permanency to the new curl configuration.
In general, permanent hair waving is usually carried out by subjecting the hair to reagents containing a free--SH group or thiol. These materials are also called mercaptans. In this treatment, the hair is usually first wound on rollers and then saturated with thiol. The thiol waving agent acts to break the disulfide bonds within the hair fiber forming thiol groups in the hair protein and disulfide bonds between two thiol waving agent molecules. The chemistry involved in the reaction of the mercaptan with the cystine disulfide bonds in the hair fiber is illustrated by the following chemical equation: EQU KSSK+2RSH.revreaction.2KSH+RSSR
When a sufficient number of hair disulfide bonds have been broken, the hair is realigned to pair previously unpaired hair protein thiol groups opposite each other. At this point, the hair is rinsed, removing the unreacted thiol waving agent and disulfide reaction product formed from it. Then, the hair is saturated with an oxidizing agent, or neutralizer, such as hydrogen peroxide or bromate salt, to reform disulfide bonds between the newly paired hair protein thiols, thereby giving the hair a new configuration or wave, or adding curl to the hair. By rebonding the sites of the reduced keratin in their new curled configuration, a permanent set which is impervious to water is established.
The rebonding of the reduced sites accomplished by the action of the chemical oxidizing agent is illustrated by the following chemical reaction: EQU 2KSH+H.sub.2 O.sub.2 .fwdarw.KSSK+2H.sub.2 O.
Presently, two types of permanent wave compositions are most often employed to saturate the hair with the requisite thiol waving agent. One such composition is based upon the use of ammonium thioglycolate while the other conventional composition employs glyceryl monothioglycolate (GMT). The principal differences between these two hair waving compositions is the pH at which these compositions operate, with the GMT composition being capable of providing the desired permanent wave to the hair at a lower pH, usually ranging between 6.5 and 8.
In addition to the thiol waving agent, these hair waving compositions typically incorporate hair enhancing additives, such as conditioning agents and fragrances to provide added luster and sheen to the hair, as well as a pleasing aroma. In the hair waving compositions employing the ammonium thiolgylcolate, these additives are usually mixed directly with the ammonium thiolgylcolate to form a single, permanent waving composition.
However, in the permanent waving compositions employing GMT, hair enhancing additives are typically mixed with the GMT immediately prior to application of the composition to the hair. As a result, any hair enhancing additives to be employed with the permanent wave composition must be packaged and distributed separately from the GMT-based permanent wave composition.
This requirement for separate packaging is due to the propensity GMT has to react or break down when mixed with other components for long periods of time. Consequently, hair waving compositions employing GMT as the thiol waving agent require two independent, separate containers, one container for the GMT hair waving composition and a second container for the hair enhancing additives.
Although GMT based permanent waved compositions have been widely sold and distributed, the requirement that these permanent waving composition be distributed in two separate and distinct containers has led to various packaging and distribution problems inherent in creating and distributing a two-container product which is both functional and visually pleasing. Alternatively, these prior art products have been sold as a single component product with the more desirable conditioning and fragrance additives being sacrificed.
Therefore, it is a principal object of the present invention to provide a permanent waving composition which is formulated for optimum hair waving and conditioning, while also providing a unique, visually distinctive appearance.
Another object of the present invention is to provide a permanent wave composition having the characteristic features defined above which is formulated to provide a plurality of separate and distinct phases or layers which remain immiscible throughout the distribution process and are homogeneously mixable upon use.
Another object of the present invention is to provide a permanent wave composition having the characteristic features described above which provides the enhanced, visually distinctive multi-phases, without in any way compromising the efficacy of the permanent wave composition.
Another object of the present invention is to provide a permanent wave composition having the characteristic features described above which provides a multi-phase composition for one of the components of a GMT based permanent waved composition.
Other and more specific objects will in part be obvious and will in part appear hereinafter.